Dr. William McLaney Maribel Mafla Ana María Arias

125 Pages·2010·2.95 MB·English

2010

THE THREAT TO BIODIVERSITY AND ECOSYSTEM

FUNCTION OF PROPOSED HYDROELECTRIC DAMS
IN THE LA AMISTAD WORLD HERITAGE SITE,
PANAMA AND COSTA RICA.

Dr. William O. McLarney

Lic. Maribel Mafla H
Lic. Ana María Arias
Lic. Danielle Bouchonnet

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THE THREAT TO BIODIVERSITY AND ECOSYSTEM FUNCTION IN THE LA AMISTAD
WORLD HERITAGE SITE, PANAMA AND COSTA RICA, FROM PROPOSED
HYDROELECTRIC DAMS

A follow-up to McLarney and Mafla (2007):

Probable Effects on Aquatic Biodiversity and Ecosystem Function of Four Proposed
Hydroelectric Dams in the Changuinola/Teribe Watershed, Bocas del Toro, Panama, with Emphasis on
Effects Within the La Amistad World Heritage Site

With consideration also of La Amistad/Costa Rica and the Pacific Slope of La Amistad.

Dr. William O. McLarney
Lic. Maribel Mafla H.
Lic. Ana Maria Arias
Lic. Danielle Bouchonnet

Programa de Biomonitoreo
Asociación ANAI

Contact Information:

Asociación ANAI (Costa Rica): ANAI, Inc. (United States):
Apdo. 170-2070 1120 Meadows Rd.
Sabanilla de Montes de Oca Franklin, North Carolina 28734
Costa Rica, C.A. USA
Phone: [phone] Phone/fax: [phone]
(506) 2756-8120 E-mail: [email protected]
Fax: [phone]
E-mail: [email protected]
[email protected]

Respectfully submitted to:

UNESCO World Heritage Committee

February, 2010

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Table of Contents

EXECUTIVE SUMMARY 5
RESUMEN EJECUTIVO 8
INTRODUCTION 11
DAMS AS BARRIERS, AND THE IMPORTANCE OF DIADROMY 13
EFFECTS OF DAMS ON DIADROMOUS ANIMALS IN MESOAMERICA AND THE CARIBBEAN 17
EVENTS SINCE 2008 19
1. Social, Political and Legal Events: 19
Panama-Atlantic slope: 19
Panama-Pacific slope: 19
Costa Rica-Pacific slope: 20
Costa Rica-Atlantic slope: 20
2. Biological Investigations: 21
Panama: 21
Costa Rica – Pacific slope: 25
Costa Rica – Atlantic slope: 26
Darwin Initiative: 26
THE LA AMISTAD AREA AND ITS WATERSHEDS 28
THE LA AMISTAD AREA 28
FLUVIAL SYSTEMS OF LA AMISTAD, WITH COMMENTS ON PLANNED DAMS 30
Atlantic slope – Panama: 30
Changuinola/Teribe watershed 30
Atlantic slope – Costa Rica: 31
Sixaola/Telire watershed 32
Estrella watershed 33
Banano watershed 33
Matina watershed 34
Pacific slope – Costa Rica: 34
Grande de Terraba Watershed 34
Pacific slope – Panama: 35
Chiriqui Viejo, Piedras/Chico and Chiriqui watersheds 35
Conclusion: 36

THE AQUATIC FAUNA OF LA AMISTAD 37
FISH 37
Introduction and Overview: 37
ATLANTIC SLOPE SPECIES: 39
Family Anguillidae 39
Anguilla rostrata 39
Family Atherinidae 39
Atherinella chagresi 39
Family Gobiesocidae 40
Gobiesox nudus 40
Family Gerreidae 41
Eugerres plumieri 41
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Family Haemulidae 41
Pomadasys crocro 41
Family Mugilidae 42
Agonostomus monticola 42
Joturus pichardi 43
Family Gobiidae 44
Awaous banana 44
Sicydium spp. 45
Family Eleotridae 46
Gobiomorus dormitor 46
OTHER FISHES OF CONCERN: 48
 Potamodromous species: 48
 Cryptic diadromous species: 48
 Euryhaline facultative wanderers: 49
 “New” species: 49
 Pacific slope diadromous species: 50

MACROINVERTEBRATES 51
BENTHOS: 51
SHRIMPS: 53
Overview: 53
ATYIDAE – ATLANTIC SLOPE: 55
Atya inocous 55
Atya scabra 55
Jonga serrei 55
Micratya poeyi 55
Potimirim glabra, Potimirim mexicana, and Potimirim potimirim 55
PALAEMONIDAE – ATLANTIC SLOPE: 56
Macrobrachium acanthurus 56
Macrobrachium carcinus 56
Macrobrachium crenulatum 56
Macrobrachium heterochirus 56
Macrobrachium olfersi 57
ATYIDAE – PACIFIC SLOPE: 57
PALAEMONIDAE – PACIFIC SLOPE: 57
SUMMARY: 58

SECONDARY EFFECTS OF SPECIES EXTIRPATIONS OR DRASTIC POPULATION
DECLINES ABOVE DAMS 59
Predator – prey relationships: 59
Frugivores: 59
Omnivores, herbivores and detritivores: 60
General considerations: 60
Effects in high altitude streams: 60
1. Sediment dynamics: 62
2. Breakdown of allochthonous vegetable matter: 63
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3. Water and substrate chemistry: 64
4. Algal biomass and diversity: 65
5. Structure of the benthic macroinvertebrate assemblage: 66
Conclusion: 67

UNIQUE CHARACTER OF LA AMISTAD FLUVIAL ECOSYSTEMS AND THEIR RELATION TO OTHER
ECOSYSTEMS 68
Importance of high altitude streams: 68
Uniqueness of La Amistad fluvial ecosystems: 70
Terrestrial systems within the World Heritage Site: 72
Downstream effects of natural barriers: 73
On site and downstream effects of dam/reservoir complexes: 74
Overview and reservoir effects: 74
Downstream effects: 76
Dewatering 77
Flow rate 77
Sediment transport 77
Temperature regimes 78
Changes in water chemistry 79

MITIGATION 80
Fish passage strategies: 80
Artificial rearing of migratory species: 82
The “landlocking” phenomenon: 83
Downstream mitigation: 84
Mitigation at the regional scale: 84
Conclusion: 85

RECOMMENDATIONS 87
ACKNOWLEDGEMENTS 89
REFERENCES CITED 90
APPENDIX I. TABLES 112-116
APPENDIX II. MAPS 117-123

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EXECUTIVE SUMMARY

In this paper we expand and update our previous report “Probable Effects on Aquatic
Biodiversity and Ecosystem Function of Four Proposed Hydroelectric Dams in the Changuinola/Teribe
Watershed, Bocas del Toro, Panama, with Emphasis on Effects Within the La Amistad World Heritage
Site”, taking into account events occurring since that report was presented in February, 2008 and
expanding coverage to include all of the La Amistad World Heritage Site watersheds in both countries
and on both sides of the Continental Divide. This is necessary because it has become increasingly
apparent that, chiefly as a consequence of dam proposals and in direct contravention of one of the
stated purposes for declaring the La Amistad National Parks, all of the major watersheds within the
World Heritage Site are threatened with multiple species extirpations and consequent secondary effects
which stand to grossly alter the character of ecosystems within the Site and the surrounding protected
areas and indigenous territories making up the La Amistad Biosphere Reserve. For the sake of
convenience, in much of the discussion we divide the La Amistad region into 4 sectors – Costa Rica and
Panama, Atlantic and Pacific slopes.
While this report focuses on biological events and predictions, we must take note of the
numerous protests against dam plans and associated development which have occurred in all 4 sectors,
based not only on environmental issues, but also reflecting valid socio-cultural, indigenous rights and
local economic concerns. Of particular concern are open pit mining plans being developed in Bribri
territory on the very periphery of the World Heritage Site on the Atlantic slope of Costa Rica, and which
are perceived as related to nearby dam sites.
Results of several important biological investigations in the La Amistad area have been
published since our last report. These include inventories of fish and macroinvertebrates carried out by
University of Costa Rica biologists and sponsored by ICE in the Grande de Terraba River drainage on the
Paciflc slope of Costa Rica, advances in Asociacion ANAI’s continuing biomonitoring investigations on the
Atlantic slope of that country, and an ongoing binational Darwin Initiative inventory focusing on the
World Heritage Site, which has already reported numerous new country records and discovered 31
species of animals and plants new to science.
However, perhaps the most immediately significant new investigation is a series of inventories
undertaken by the Smithsonian Tropical Research Institute (STRI) in the portion of the Changuinola River
watershed which would be directly affected by the CHAN-75 and CHAN-140 dams. Along with important
new species records, the STRI report confirms the ANAI biomonitoring team’s assertion (based on
monitoring in the Atlantic slope watersheds of Costa Rica and non-quantitative surveys in the
Changuinola/Teribe watershed of Panama) of overwhelming dominance by diadromous migratory fish
and shrimp in streams at middle and upper elevations on the Atlantic slope of the La Amistad area.
Unfortunately, the Executive Summary of the extremely long (total 1,081 pages) STRI report
attempts to serve public relations functions by underplaying the significance of diadromy and glossing
over problems and limitations which are acknowledged in the full text. This tendency is extended and
exacerbated in the recently published mitigation proposal by the engineering firm AES Changuinola and
the consulting firm MWH which does however constitute an important new bibliographic resource.
Descriptive sections of the present ANAI report place the rivers which arise within the La
Amistad World Heritage Site in a geographic context of the ca. 10,000 sq. km. La Amistad Biosphere
Reserve, and review the fish and macroinvertebrate taxa known from these watersheds, with emphasis
on diadromous species known to occur within the World Heritage Site.
For each of the 4 sectors of the La Amistad area we analyze all publicly available information on
proposed dams and relate it to the threat of species extirpation and related ecological consequences.
For the Pacific slope of Panama, we note that all access by diadromous species to streams within the
World Heritage Site is already blocked by existing or nearly completed dams, leading to a hypothesis of
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total or near-total species extirpation. On the Atlantic slope of Panama, the only significant change
since 2007 is progress toward completion and closure of the CHAN-75 and Bonyic Dams. We report on
proposals for 8 dams on the Atlantic slope of La Amistad/Costa Rica, and plans for one large and several
smaller dams on the Pacific slope of that country. We conclude that if all presently proposed dams are
constructed, 67% of the total watershed area of the La Amistad World Heritage Site will become
inaccessible to diadromous and other upstream/downstream migratory fauna. As maps in this report
suggest, similar figures could be derived for all of the upland protected areas and indigenous territories
in the La Amistad region.
In the following discussion of the biological aspects of the dam threat, we will emphasize the
Atlantic slope watersheds of both countries, for two reasons: 1) More than 90% of the World Heritage
Site is located on that side of the Continental Divide and 2) Our knowledge of the biology of the Atlantic
slope streams is much more detailed. With these limitations acknowledged, and recognizing also that
the World Heritage Site and contiguous protected areas on the Pacific slope for the most part consist of
a high altitude fringe, we must mention that, at the watershed level, the threat (and in Panama, losses
to date) in Pacific slope watersheds is very comparable.
For the Atlantic slope we identify at least 16 diadromous species (8 fish and 8 shrimps) which
will probably be extirpated from major portions of the World Heritage Site if existing dam plans are
realized, and also discuss implications for potamodromous species (those which perform obligatory
migrations entirely within fresh water) and others.
We argue that the ecological effects of predictable species extirpations will not be limited to a
loss of biodiversity at the species level and that, in fact, secondary effects will be more significant. In
addition to noting the implications of loss of species of seed dispersers and alteration of predator-prey
relationships, we draw on a large, long term body of research from Puerto Rico (where rivers have a
similar diadromous fish and shrimp fauna) and elsewhere to show how elimination of omnivores,
herbivores and detritivores (categories which include all the shrimp and the most abundant fishes of the
La Amistad region) affects sediment dynamics, breakdown of allochthonous vegetable matter, water
and substrate chemistry, algal biomass and diversity and structure of the benthic macroinvertebrate
assemblage. We apply the principles of the River Continuum Concept to show that loss of these
“ecosystem engineers” would have profound negative effects on the fluvial systems of the La Amistad
area within and downstream of the World Heritage Site, all the way to the estuaries.
A large body of experience at existing dams worldwide suggests that causes outside the World
Heritage Site (dams) will have negative effects within the Site which will in turn contribute synergistically
to effects occurring downstream. In addition to habitat loss in areas occupied by dam sites, reservoirs
and downstream dewatered reaches, the effects of downstream alterations in flow rate and periodicity,
sediment transport and deposition, temperature, and water chemistry will be exacerbated by biological
impoverishment of the upper reaches of rivers.
In general, we take exception to government policies which permit and facilitate massive
species extirpations and associated ecological impacts within a World Heritage Site, while noting that in
this particular case the threat is to a nearly unique ecosystem. The faunal assemblage typical of high
gradient streams in the La Amistad area, with high diversity in the lower reaches, coupled with
dominance by Sicydium gobies and shrimps in the upper watersheds, occurs in only 3 other small areas
in the Caribbean Basin. In large part because of the existence of the World Heritage Site and its
surrounding complex of other protected areas, La Amistad represents our best chance to permanently
protect this unique ecosystem.
The AES/MWH mitigation proposal for the CHAN-75 and CHAN-140 dams provides an
opportunity to critique the concept of mitigation as it relates to this particular ecosystem. Beginning
with the patently false assertion that the dams will occasion no alteration in downstream habitats and
ecosystems, they propose as the best mitigation for upstream effects an aquaculture system which
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exists only conceptually and would be impossible to implement in a way compatible with dam
construction schedules. While this mitigation proposal, like those previously presented in less
developed form in the Environmental Impact Assessments for the Changuinola and Bonyic Dams,
suggests a lack of willingness to sincerely address the problem of upstream species extirpations, the
treatment of aquaculture and other options in it does serve to advance the discussion of mitigation
alternatives and reinforces our conclusion: Based on all available information, we conclude that there is
no possibility of significant mitigation for the ecological alterations which would result from completion
of existing dam plans in the La Amistad region.
Recognizing that UNESCO, ANAM, MINAET and all others involved face clearly defined limits to
their authority, we suggest that the threats facing the fluvial and other ecosystems of the La Amistad
area cannot be dealt with solely through implementing policies within jurisdictional boundaries. The
nature of the rivers of the La Amistad area, particularly their diadromous component, and their relation
to terrestrial and marine environments, demands a watershed conservation approach, extending across
all kinds of boundaries.
Our previous report to UNESCO was in support of a petition soliciting the declaration of La
Amistad as a World Heritage Site in Danger; this has not yet occurred. In the interim it has become clear
that the threat presented by proposed dams extends beyond the Changuinola/Teribe watershed in
Panama. It is binational in nature and has the potential to grossly alter the natural character of the
World Heritage Site and other areas on both sides of the Continental Divide.
At this point, in recognition of the greater severity of the threat, we recommend that the
UNESCO World Heritage Committee reopen the discussion of possible listing of the binational La
Amistad World Heritage Site as a World Heritage Site in Danger, in the context of considering all
alternatives for the protection of its biodiversity. We would also strongly suggest to UNESCO, the two
national governments and all other concerned parties that all discussions related to this threat take
place in a context which recognizes the ultimate impossibility of protecting the biodiversity and
ecosystem integrity of the La Amistad World Heritage Site without taking into account entire
watersheds, from the Continental Divide to the sea.

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RESUMEN EJECUTIVO

En este documento expandimos y actualizamos nuestro previo documento “Posibles efectos
sobre la biodiversidad acuática y la función de ecosistemas de las cuatro represas hidroeléctricas
propuestas en la cuenca hidrológica Changuinola/Teribe, Bocas del Toro, Panamá con énfasis en el Sitio
de Patrimonio Mundial La Amistad”, considerando los sucesos ocurridos desde que ese informe fuera
presentado en febrero del 2008 y expandiendo el área de análisis a toda la región de Patrimonio
Mundial en las cuencas de ambos países y a ambos lados de la división continental de aguas. Esto se
hace necesario porque está llegando a ser obvio que mayormente como consecuencia de la propuesta
de construcción de las represas, y contraviniendo directamente el propósito de la formación de La
Amistad como parques nacionales, la mayor cantidad de cuencas en este Sitio de Patrimonio Mundial
están siendo amenazadas con la extirpación de un gran número de especies y con consecuentes efectos
secundarios que alterarán el carácter de sus ecosistemas, de las áreas protegidas y de territorios
indígenas aledaños que en su conjunto forman la Reserva de la Biosfera de La Amistad. Para facilitar
algunos aspectos del análisis, dividimos la región de La Amistad en 4 sectores - Costa Rica y Panamá,
Vertientes Atlántica y Pacífica.
Mientras este informe se enfoca en sucesos y predicciones biológicas, debemos considerar
también las numerosas protestas que se están llevando a cabo contra los planes de construcción de las
represas y el desarrollo asociado a ellas en los 4 sectores; protestas basadas no sólo en aspectos de
protección del medio ambiente sino también en la validez socio-cultural de los planes, y su impacto
contra la economía local y los derechos de los indígenas. De particular preocupación son los planes
mineros a tajo abierto que están siendo desarrollados en el territorio Bribri en la periferia misma del
Sitio de Patrimonio Mundial sobre la vertiente atlántica de Costa Rica, que son percibidos como planes
relacionados a la construcción de las represas.
Desde la presentación de nuestro último informe, se han publicado resultados de importantes
investigaciones biológicas en el área de La Amistad. Éstos incluyen inventarios de peces y
macroinvertebrados llevados a cabo por biólogos de la Universidad de Costa Rica con el apoyo de ICE en
el drenaje del Río Grande de Terraba en la Vertiente Pacífica de Costa Rica; progresos en las
investigaciones de monitoreo de la Asociación ANAI en la Vertiente Atlántica de ese país; y el inventario
binacional de la Iniciativa Darwin que se enfoca en el Sitio de Patrimonio Mundial que viene reportando
numerosos nuevos records y descubriendo 31 especies de plantas y animales nuevas para la ciencia.
Sin embargo, quizás la investigación más significante es una serie de inventarios llevados a cabo
por el Instituto de Investigación Tropical Smithsonian (STRI) en la porción de la cuenca del Río
Changuinola que puede ser directamente afectada por las represas CHAN-75 y CHAN-140. Además de
registrar la existencia de nuevas especies, el informe de STRI confirma la afirmación del equipo de
monitoreo de ANAI (basado en el monitoreo de las cuencas en la Vertiente Atlántica de Costa Rica y las
encuestas no cuantitativas en la cuenca Changuinola/Teribe de Panamá) de la existencia de una
abrumadora dominancia de peces y camarones diadromos (migratorios) en ríos y quebradas en
elevaciones medias y altas de la Vertiente Atlántica del área de La Amistad.
Desafortunadamente, el resumen ejecutivo del extenso informe de STRI (con un total de 1,081
páginas) intenta cumplir más funciones de relaciones públicas al reducir la importancia de diadromia y al
pasar por encima problemas y limitaciones que son reconocidos en el texto completo del informe. Esta
tendencia es extendida y exacerbada en la propuesta de mitigación recientemente publicada por la
firma de ingenieros AES Changuinola y la firma consultora MWH que constituye, sin embargo, un nuevo
recurso bibliográfico importante.
Secciones descriptivas del presente informe de ANAI ubica los ríos que surgen en el Sitio de
Patrimonio Mundial La Amistad en un contexto geográfico de cerca de 10,000 km2 de la Reserva Biosfera
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La Amistad, y revisa los taxones de peces y macroinvertebrados de esas cuencas con énfasis en especies
diadromas que han sido identificadas en el Sitio de Patrimonio Mundial.
Para cada uno de los 4 sectores del área de La Amistad analizamos toda la información pública
disponible sobre las propuestas de construcción de las represas y la conectamos con la amenaza de
extirpación de especies y las consecuencias ecológicas relacionadas. Para la Vertiente Pacífica de
Panamá, anotamos que todo el acceso de las especies diadromas a los ríos y quebradas dentro del Sitio
de Patrimonio Mundial está actualmente bloqueado por las represas existentes o casi terminadas, lo
que nos lleva a apoyar la hipótesis de extirpación total o casi total de las especies. En la Vertiente
Atlántica de Panamá, el único cambio significativo desde 2007 es el progreso hacia la culminación de las
represas CHAN-75 y Bonyic. Informamos sobre 8 de las represas propuestas en las cuencas de la
Vertiente Atlántica de La Amistad/Costa Rica y sobre los planes existentes para construir una represa
grande y varias represas pequeñas en la Vertiente Pacífica de ese país. Concluimos que si todas las
actuales represas propuestas son construidas, 67% del total del área de las cuencas hidrológicas del Sitio
de Patrimonio Mundial La Amistad llegará a ser inaccesible a diadromos y a otro tipo de fauna
migratoria río arriba o río abajo. Como lo sugieren los mapas en este informe, porcentajes similares
pueden ser estimados para todas las áreas protegidas y los territorios indígenas en la región de La
Amistad.
En la discusión sobre los aspectos biológicos de la amenaza de las represas, enfatizaremos la
situación de las cuencas en la Vertiente Atlántica en los dos países, por dos razones: 1) Más del 90% del
Sitio de Patrimonio Mundial está ubicado a ese lado de la División Continental de aguas y 2) Nuestro
conocimiento de la biología acuática de la Vertiente Atlántica es mucho más detallado. Con el
reconocimiento de estas limitaciones y reconociendo también que el Sitio de Patrimonio Mundial y las
áreas protegidas contiguas en la Vertiente Pacífica en su mayor parte consisten de una franja de gran
altitud, mencionaremos que, al nivel de cuencas, la amenaza (y en Panamá las perdidas a la fecha) en
las cuencas de la Vertiente Pacífica es muy comparable.
Para la Vertiente Atlántica identificamos al menos 16 especies diadromas (8 de peces y 8 de
camarones) que probablemente serán extirpados de la mayor porción del Sitio de Patrimonio Mundial si
los planes existentes de construcción de las represas son ejecutados, y también discutimos las
implicancias para las especies potamodromos (animales obligados a migraciones largas en aguas dulce
para completar su ciclo de vida) y otras especies.
Sostenemos que los efectos ecológicos de las predecibles extirpaciones de especies no estarán
limitados a la pérdida de biodiversidad a nivel de las especies y que, de hecho, otros efectos secundarios
serán aún más significativos. Además de considerar las implicancias de la pérdida de especies de
dispersores de semillas y de la alteración de las relaciones de predadores-presas, nos basamos en una
abundante información acumulada tras un largo periodo de investigación en Puerto Rico (donde los ríos
tienen una fauna similar de peces y camarones diadromos) y en otros lugares para mostrar como la
eliminación de omnívoros, herbívoros y detritívoros (categorías que incluyen todos los camarones y la
mayor cantidad de peces de la región de La Amistad) afecta las dinámicas de sedimentación,
descomposición de materia vegetal alóctona, la química del agua y los substratos, biomasa de algas y la
estructura del ensamblaje de macroinvertebrados bentónicos. Aplicamos los principios del Concepto
del Continuo del Río para mostrar que la pérdida de estos “ingenieros de ecosistemas” podría tener
profundos efectos negativos en los sistemas fluviales del área de La Amistad, río abajo del Sitio de
Patrimonio Mundial, y hasta los estuarios.
Una gran cantidad de experiencia acumulada en existentes represas a nivel mundial sugiere que
las causas fuera del Sitio de Patrimonio Mundial (represas) tendrán efectos negativos dentro del Sitio lo
que en su momento contribuirá sinergéticamente a efectos que ocurrirán río abajo. Además de la
pérdida de hábitat en las áreas ocupadas por las represas, reservorios y trechos de desagüe, los efectos
por la alteración del flujo de agua río abajo, en cantidad y periodicidad, transporte y deposición de
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